Various light deflectors that deflect light have conventionally been studied. Light deflectors are devices indispensable to, for example, laser scanners used in laser printers or the like. Examples of conventional light deflectors that are used include polygon scanners, galvanometer scanners, and MEMS mirrors. However, since such polygon scanners, galvanometer scanners, MEMS mirrors, or the like include a mobile unit (mechanical mechanism) for moving parts, there is a problem in that a failure easily occurs. For this reason, there is demand for the development of light deflectors capable of deflecting light without including a mobile unit.
In response to that demand, a light deflector as disclosed in Patent Document 1 below has been proposed. This light deflector does not include a mobile unit, and deflects light with use of the fact that the refractive indices of liquid crystals are modulated by application of voltage. Through this, it is possible to reduce the occurrence of failures and achieve high reliability.
Now, a conventional light deflector will be described with reference to FIGS. 7A and 7B. FIG. 7A is a cross-sectional view of a conventional light deflector, and FIG. 7B is a cross-sectional view of the light deflector taken along line A-A in FIG. 7A. A light deflector 50 shown in FIGS. 7A and 7B includes a liquid crystal deflection element 501 and three pairs of electrodes 502a, 502b, and 502c disposed in the periphery of the liquid crystal deflection element 501. The liquid crystal deflection element 501 includes a liquid crystal 503 having a triangular shape in cross section and a dielectric 504 having a shape complementary to that of the liquid crystal 503. The dielectric 504 is disposed on the inclined face side of the liquid crystal 503, as a result of which the liquid crystal deflection element 501 as a whole is configured in a rectangular shape in cross section. The dielectric 504 may be made of, for example, a polymeric resin or the like such as a plastic, or glass or the like. The three pairs of electrodes 502a, 502b, and 502c are each disposed such that the two electrodes face each other with the liquid crystal deflection element 501 therebetween.
By applying voltage between each of the three pairs of electrodes 502a, 502b, and 502c, the refractive index of the liquid crystal 503 is modulated, and light incident on the liquid crystal deflection element 501 is deflected. Note that although the three pairs of electrodes 502a, 502b, and 502c are provided in the configuration shown in FIGS. 7A and 7B, a configuration is also possible in which only any one or two out of these three pairs of electrodes are provided.
As indicated by an arrow 505 in FIG. 7A, light enters the liquid crystal deflection element 501 from the incidence end face of the liquid crystal 503 (lower face in FIG. 7A). Note that the pair of electrodes 502b is desirably a pair of transparent electrodes so that light can pass through the pair of electrodes 502b. 
When a refractive index NL of the liquid crystal 503 and a refractive index ND of the dielectric 504 are the same value in a state in which no voltage is applied between the pairs of electrodes 502a, 502b, and 502c, light travels straight in a direction indicated by an arrow 505s in FIG. 7A without being refracted. When the refractive index NL of the liquid crystal 503 becomes higher than the refractive index ND of the dielectric 504 as a result of application of voltage between the pairs of electrodes 502a, 502b, and 502c, light is refracted in a direction indicated by an arrow 505h in FIG. 7A. Furthermore, when the refractive index NL of the liquid crystal 503 becomes lower than the refractive index ND of the dielectric 504 as a result of application of voltage between the pairs of electrodes 502a, 502b, and 502c, light is refracted in a direction indicated by an arrow 505m in FIG. 7A. In this way, the angle of deflection of light can be modulated by controlling the voltage applied between the pairs of electrodes 502a, 502b, and 502c. 
Furthermore, a configuration as shown in FIG. 8 is also possible in which a plurality of (three in FIG. 8) liquid crystal deflection elements 501a, 501b, and 501c are arranged in the lateral direction. In a light deflector 60 in FIG. 8, dielectrics 504a, 504b, and 504c are respectively disposed on the inclined face side of the liquid crystals 503a, 503b, and 503c. The dielectrics 504a, 504b, and 504c are configured as a single entity. A dimension Wa of the liquid crystal deflection element 501a, a dimension Wb of the liquid crystal deflection element 501b, and a dimension Wc of the liquid crystal deflection element 501c in the direction of light deflection (right-left direction in FIG. 8) are all the same dimension (Wa=Wb=Wc). Furthermore, a tilt angle θa of the inclined face of the liquid crystal 503a, a tilt angle θb of the inclined face of the liquid crystal 503b, and a tilt angle θc of the inclined face of the liquid crystal 503c are all the same angle (θa=θb=θc). Note that the aforementioned three pairs of electrodes are not shown in FIG. 8.
Arranging the liquid crystal deflection elements 501a, 501b, and 501c in this manner enables deflection of wide light (e.g., linear light, planar light, or the like).